### Video Transcript

Find the lengths of line πΆπ· and line π·π΄.

First, weβre interested in line πΆπ· and, second, line π·π΄. Before we can determine the lengths of these lines, we need to think about what we know about this figure. Line π·π΄ is parallel to line πΆπ΅. And line π·πΆ is parallel to line π΄π΅. This tells us that in this shape, opposite sides are parallel. And so we can say that π΄π΅πΆπ· is a parallelogram. And in a parallelogram, opposite sides are equal in length. Line π·πΆ is opposite line π΄π΅. And therefore, π·πΆ and π΄π΅ are equal in length. If π·πΆ equals π΄π΅, then they both measure 15 centimeters. We can also say that line π΄π· is opposite line π΅πΆ which makes line π΄π· equal to line π΅πΆ and a measure of 13 centimeters. πΆπ· equals 15 centimeters and π΄π· equals 13 centimeters. Notice that we can write the name of the line with the end points in either order. π·π΄ and π΄π· are the same lines, and πΆπ· and π·πΆ are also the same lines.